Photo credit: Wiki Commons

Imagine waiting in line to buy the latest smart phone, laying down a great deal of money for it, then suddenly being told that if you don’t plug in your new purchase within 15 minutes, it will never work. High tech vendors would hate this approach, as would their customers, but for anyone who deals with blood as a commodity, the scenario captures an unpleasant reality.

Refrigerated blood can be stored for about 42 days, at which point it must be discarded. Blood can also be kept frozen indefinitely, which means that large quantities could more easily be transported and kept on hand for emergency conditions, such as near a battlefield where wounded soldiers are to be treated. However, blood cells must be protected from ice crystals in a mixture of 40 percent glycerol. “Once you thaw that unit, you have to deglycerolize it,” says Robert Ben, a professor in the University of Ottawa’s Department of Chemistry. “If you put it directly into the bloodstream you would have extensive hemolysis, the rupturing of blood cells because of the high osmolality caused by the glycerol solution.”

Ben says that it can take more than an hour to reduce the glycerol concentration to one percent, the acceptable level for injection. That can be far too long to wait under emergency conditions where a patient can bleed out in a matter of minutes. Nor can the product be prepared in advance. Like the now-or-never smart phone, once blood is thawed it must be used immediately or thrown away. 

This conundrum may be at an end if Ben’s latest research can be implemented under clinical conditions. He and his colleagues have been developing a new class of small-molecule ice recrystallization inhibitors that could protect blood cells from the effects of drastic temperature change without the need for a time-consuming removal procedure. “Because we’re addressing the damage that occurs from ice recrystallization head on, we can now dramatically cut back on the amount of glycerol that we would use to freeze the unit,” he says. With proportions as low as 10 to 15 percent, as well as using microfluidic technology for deglycerolization, frozen blood could quickly become viable under even the tightest schedule.

Ben’s interest in the subject was sparked in the late 1990s, starting with the question of how some organisms such as fish and amphibians produce peptides and glycoconjugates that allow their bodies to deal with freezing temperatures. After choosing blood cells as a model for investigation, he quickly became aware of the urgent practical interest in resolving some of the problems surrounding the preservation of blood products. He also notes that natural anti-freeze proteins were large structures that could interfere with cellular health. In the search for alternatives, he identified amphiphilic molecules based on carbohydrates and amino acids that were far lighter but just as effective at preventing the formation of ice crystals, a finding that was recently published in ACS Omega.

It was during the course of this work that Ben became aware of the widespread interest in the prospect of freezing not just blood but various types of tissue and even entire organs, all with the aim of making these vital medical resources more widely available. It was at a 2015 cryobiology summit in California that Ben heard a speaker put forward the analogy to selling electronics that must be immediately used, an image that captured his imagination. “That’s a poor marketing strategy,” he says, “but it’s exactly what we’re doing in modern regenerative medicine and tissue engineering.”